ABSTRACT

Mitochondrial impairment is a hallmark feature of neurodegenerative disorders, such as Parkinson disease, and PRKN/parkin-mediated mitophagy serves to remove unhealthy mitochondria from cells. Notably, probiotics are used to alleviate several symptoms of Parkinson disease including impaired locomotion and neurodegeneration in preclinical studies and constipation in clinical trials. There is some evidence to suggest that probiotics can modulate mitochondrial quality control pathways. In this study, we screened 49 probiotic strains and tested distinct stages of mitophagy to determine whether probiotic treatment could upregulate mitophagy in cells undergoing mitochondrial stress. We found two probiotics, Saccharomyces boulardii and Lactococcus lactis, that upregulated mitochondrial PRKN recruitment, phospho-ubiquitination, and MFN degradation in our cellular assays. Administration of these strains to Drosophila that were exposed to paraquat, a mitochondrial toxin, resulted in improved longevity and motor function. Further, we directly observed increased lysosomal degradation of dysfunctional mitochondria in the treated Drosophila brains. These effects were replicated in vitro and in vivo with supra-physiological concentrations of exogenous soluble factors that are released by probiotics in cultures grown under laboratory conditions. We identified methyl-isoquinoline-6-carboxylate as one candidate molecule, which upregulates mitochondrial PRKN recruitment, phospho-ubiquitination, MFN degradation, and lysosomal degradation of damaged mitochondria. Addition of methyl-isoquinoline-6-carboxylate to the fly food restored motor function to paraquat-treated Drosophila. These data suggest a novel mechanism that is facilitated by probiotics to stimulate mitophagy through a PRKN-dependent pathway, which could explain the potential therapeutic benefit of probiotic administration to patients with Parkinson disease.

 抽象的

线粒体损伤是帕金森病等神经退行性疾病的一个标志性特征，PRKN/parkin 介导的线粒体自噬可以从细胞中清除不健康的线粒体。值得注意的是，益生菌用于缓解帕金森病的多种症状，包括临床前研究中的运动障碍和神经退行性变以及临床试验中的便秘。有一些证据表明益生菌可以调节线粒体质量控制途径。在这项研究中，我们筛选了 49 种益生菌菌株并测试了线粒体自噬的不同阶段，以确定益生菌治疗是否可以上调经历线粒体应激的细胞中的线粒体自噬。我们发现两种益生菌，布拉氏酵母菌和乳酸乳球菌，在我们的细胞检测中上调线粒体 PRKN 募集、磷酸泛素化和 MFN 降解。将这些菌株给予暴露于百草枯（一种线粒体毒素）的果蝇，可以延长寿命和运动功能。此外，我们直接观察到经过处理的果蝇大脑中功能失调的线粒体的溶酶体降解增加。这些效应在实验室条件下培养的培养物中通过益生菌释放的超生理浓度的外源可溶性因子在体外和体内得到复制。我们确定甲基异喹啉-6-羧酸酯为一种候选分子，它上调线粒体 PRKN 募集、磷酸泛素化、MFN 降解和受损线粒体的溶酶体降解。在蝇食中添加甲基异喹啉 6- 羧酸酯可恢复百草枯处理的果蝇的运动功能。 这些数据表明，益生菌通过 PRKN 依赖性途径促进线粒体自噬的新机制，这可以解释益生菌对帕金森病患者的潜在治疗益处。